Oakton Replaceable Electrodes pH WP 2 Pen Oakton Oakton Replaceable Electrodes pH WP 2 Pen (OK3562429)This part number is just for a replacement electrode for your Oakton pH WP 2 pen, not the actual unit itself. Optimize nutrient strength during growth, flowering, and fruiting. Reliable waterproof, dustproof housing and replaceable electrode provide long life and value, meaning you won't need to invest in or... Note: Calibration Buffer Solutions are available separately. — Ships from HF: OR, CA, CO, MI, PA USA....more info.